This invention relates to self-locking fastener assemblies and, more particularly, to an assembly having a self centering antirotation element that allows a fastener to be threaded onto an insertion member without the use of a backup tool.
A variety of self-locking fasteners or fastening assemblies are known in the art. Typical self-locking assemblies provide a mechanical interlock between an insertion member, such as a bolt, and a receiving member having a locking opening to allow a fastener, such as a nut, to be threaded onto the insertion member without the use of a backup tool. However, current self-locking assemblies require proper alignment of the insertion member to create a mechanical interlock between the components. A slight misalignment during insertion can interfere with the mechanical interlock, causing the insertion member to rotate when a fastener is threaded onto the insertion member.
The present invention provides an interlocking fastener assembly including an insertion member, a receiving member, and a fastener. The receiving member is capable of guiding a misaligned insertion member into an interlocking position so that a fastener can be rotatably applied to the insertion member without the use of a backup tool.
In an exemplary embodiment, the insertion member is generally cylindrical and includes a connecting portion, an abutment, and a locking portion between the abutment and the connecting portion. The locking portion is typically square and tapered inward toward the connecting portion of the insertion member. The square locking portion has apexes and sides extending between the apexes. The connecting portion is typically threaded and the fastener may be a nut.
The receiving member has opposite sides defining a mounting surface, a fastening surface, and a guide opening extending between the surfaces. The opening resembles a truncated star having multiple pockets with sides angled inward and joined by inward projections between the pockets. The opening has a number of pockets equal to the number of apexes on the locking portion.
The inward taper of the locking portion provides an entry portion with smaller cross dimensions than the guide opening to provide additional room for insertion. As the insertion member is further inserted the tapered sides of the locking portion engage the sides of the receiving member to center the insertion member. During the insertion process, the pockets of the receiving member receive the apexes of the locking portion. Finally, the abutment of the insertion member engages the mounting surface and the connecting portion of the insertion member extends beyond the fastening surface of the receiving member.
Angular clearance between the sides of the locking portion and the sides of the pockets allows the insertion member to rotate within the opening for a predetermine angle. A mechanical lock is formed when the sides of the locking portion engage the inner sides of the pockets. The mechanical lock prevents rotation of the insertion member, which allows a fastener to be threaded, or otherwise rotatably applied, onto the insertion member without the need for a backup tool.
These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings.